Desaturation delay, parameter for evaluating severity of sleep disordered breathing

Sleep apnea hypopnea syndrome (SAHS) is considered as a major health problem causing increased risk of cardiovascular problems. One of the most often used parameters to assess the severity of SAHS is apnea hypopnea index (AHI). It is calculated as the average amount of total cessations of breathing (apnea events) and partial reductions in breathing (hypopnea events) per hour of sleep. AHI only takes into account the total number of events regardless of their true nature. In this paper ambulatory polygraphic recordings of 19 male patients were analysed and the blood oxygen desaturation delay (BODD) studied in estimating the cardiovascular stress associated with sleep disordered breathing. The delay of the desaturation event occurring after apnea and hypopnea events were studied. Correlation with AHI and the delay parameter is modest and it shows variation between patients with similar AHI. This suggests that the delay parameter may provide additional information about the probably varying car-diovascular stress in patients with similar AHI and in the diagnostics of sleep disordered breathing in general